Java ArrayBlockingQueue poll() Method

The poll() method of ArrayBlockingQueue class retrieves the head of this queue awaiting till the specified time if essential for an element to be available, and also removes it. The method returns null if this queue is empty.

Syntax:

1.public E poll()
2.public E poll(long timeout,TimeUnit unit)throws InterruptedException

Parameters:

NA
timeout - this is the time to wait before giving up(in units of unit)
unit - this is the TimeUnit deciding how to represent the timeout parameter

Specified By:

The poll() method of ArrayBlockingQueue class is specified by poll() method in interface Queue<E>.

Return Value:

The poll() method returns this queue's head, or null if this queue is empty or if the assigned waiting time passes before element is available.

Throws:

The poll() method throws:

InterruptedException - if method is disrupted while waiting.

Example 1

import java.util.Queue;
import java.util.concurrent.ArrayBlockingQueue;
public class ArrayBlockingQueuePollExample1 {
    public static void main(String[] args) {
        int capacity=100;
        Queue<String> queue = new ArrayBlockingQueue<String>(capacity);
        queue.add("Reema");
        queue.add("Rahul");
        queue.add("Rita");
        queue.add("Ramesh");
        //retrieves and removes head of the queue
        String val = queue.poll();
        System.out.println("Head of queue is : "+val);
        System.out.println("Elements left in queue : "+queue);
    }
}

Output:

Head of queue is : Reema
Elements left in queue : [Rahul, Rita, Ramesh]

Example 2

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.TimeUnit;
public class ArrayBlockingQueuePollExample2 {
    public static void main(String[] args) throws InterruptedException {
        int capacity = 5;
        ArrayBlockingQueue<Integer> queue = new ArrayBlockingQueue<Integer>(capacity);
        queue.add(67);
        queue.add(109);
        queue.add(76);
        queue.add(876);
        //retrieves and removes the head of the queue waiting upto the specified wait time
        int val=queue.poll(678, TimeUnit.MILLISECONDS);
        System.out.println("Head of queue : "+val);
        System.out.println("Elements in queue : "+queue);
    }
}

Output:

Head of queue : 67
Elements in queue : [109, 76, 876]

Example 3

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
class Employee {
    int wages;
    String name;
    public Employee(int wages, String name) {
        this.wages = wages;
        this.name = name;
    }
    public String toString(){
        return this.name+" got "+ this.wages +" marks.";
    }
}
public class ArrayBlockingQueuePollExample3 {
    public static void main(String[] args) {
        Employee employee1 = new Employee(12000,"Reema");
        Employee employee2 = new Employee(4500,"Geetanjali");
        Employee employee3 = new Employee(1500,"Vineet");
        Employee employee4 = new Employee(1000,"Jyoti");
        int capacity = 100;
        BlockingQueue<Employee> queue = new ArrayBlockingQueue<Employee>(capacity);
        queue.add(employee1);
        queue.add(employee2);
        queue.add(employee3);
        queue.offer(employee4);
       // int val1 =queue.poll().wages;
        System.out.println(queue.peek().name+" gets the highest wages of "+queue.poll().wages);
        System.out.println(queue.peek().name+" gets the second  highest wages of "+queue.poll().wages);
    }
}

Output:

Reema gets the highest wages of 12000
Geetanjali gets the second  highest wages of 4500

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Java ArrayBlockingQueue poll() Method

Syntax:

Parameters:

Specified By:

Return Value:

Throws:

Example 1

Example 2

Example 3

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Java ArrayBlockingQueue poll() Method

Syntax: